Geomechanical and drilling fluid engineers share the common goal of maintaining proper mud weights to minimize wellbore instability during drilling. However, their efforts are often out of sync with regard to time frame, data resources, uncertainties, responsibilities, and sense of urgency. Attempts to resolve these issues in the past have encountered mixed results, primarily because the two groups utilize different technology and communicate differently.
Wellbore stability planning on complex wells is the domain of geomechanical engineers who base their recommendations on offset log analyses, well histories, geomechanical models, and knowledge of the area. Using these recommendations as guidelines, rig personnel respond to changing and unexpected well conditions by continually monitoring and adjusting mud properties and drilling practices. However, drilling fluid engineers charged with recommending and maintaining proper mud weights rarely have access, training, or time to execute geomechanical software as part of their duties. Likewise, geomechanical engineers rarely get continual updates (unless problems are encountered) and their software usually is not designed to handle certain types of data, including fuzzy data provided by wellsite drilling personnel.
Wellbore instability is one underlying cause of non-productive time during well construction. While a diversity of parameters affect the instance and degree of instability, factors including downhole mud density and equivalent circulating density profiles can contribute to wellbore instability when these densities are not appropriate for a particular formation or well profile, especially in highly deviated wells. Optimum mud weights are selected based on offset well analyses, detailed well plans, analyses and interpretation of ongoing well conditions, considerations for different density-dependent operations, and recommendations from other wellsite personnel including drilling fluids engineers, also called mud engineers. This multi-pronged approach, may result in uncertainty, lose effectiveness when information and resources are not readily available or the information is not communicated with everyone involved in making decisions and implementing solutions. Efforts can be out of sync with regard to time frame in which solutions should be implemented, data resources used to make decisions, uncertainties, responsibilities, and sense of urgency in a given situation.